Arrangements of overhead power line phase conductors obtained by Differential Evolution

This paper presents a new general method for determining the optimal arrangements of overhead power line phase conductors by optimization. The main criteria used in this optimization procedure, are the root mean square values of the magnetic flux density and the electric field strength on the border of the overhead power line's right of way. The position of each power line phase conductor is determined using the stochastic search algorithm called Differential Evolution. In the given case, the optimization goal is to find such an arrangement of phase conductors so that the tower height is minimal, whereas the values of the magnetic and electric fields on the border of the overhead power line's right of way are under the limits prescribed in the national regulations. This method is applied in order to investigate how the optimal positions of the overhead power line phase conductors change, depending on the clearances between the phase conductors of a two-conductor bundle, in the case of a vertical - double tower configuration with one overhead earth-wire.     

Effect of conductor geometry on bundle conductor galloping

A computer simulation of an elastic catenary was used to study the wake-induced galloping of a two-conductor bundle transmission line. It was shown that increasing the conductor separation reduces the region of galloping instability and decreases the amplitude of the resulting galloping. Stranded conductors are more likely to gallop at low wind speeds while smooth conductors gallop at high wind speeds. Since the fundamental frequency depends on span length, span has a large effect on galloping, with shorter spans being more susceptible. Twisting of the bundle one-half turn per span essentially eliminates galloping.     

Power-Line Communication Channel Model for Interconnected Networks—Part I: Two-Conductor System

This paper presents a generalized transmission-line approach to determine the transfer function of a power-line network of a two-conductor system (two parallel conductors) with distributed branches. The channel frequency responses are derived considering different terminal loads and branches. The model's time-domain behavior is validated using commercial power system simulation software called Alternative Transients Program–Electromagnetic Transients Program (ATP–EMTP). The simulation results from the model for three different topologies considered have excellent agreement with corresponding ATP–EMTP results. Hence, the model can be considered as a tool to characterize any given power-line channel topology that involves the two-conductor system. In the companion paper (Part II), the proposed method is extended for a multiconductor power-line system.      

安装失谐摆的大跨越分裂导线自由振动计算

安装了失谐摆的大跨越分裂导线振动特性的准确计算对于舞动分析和防舞设计有重要意义。文中基于子导线总位移的控制微分方程，推导得到子导线段自由振动的控制微分方程。针对导线运动的小应变和小转角特点，提出了大跨越分裂导线的一种新型三维有限元模型，它可以直接处理间隔棒上安装了失谐摆的情况，结合间隔棒对导线的约束关系，推导建立了单元质量和刚度矩阵，应用获得的公式体系对实际大跨越分裂导线进行了自由振动计算。注意到系统有丰富的侧向摆动模态，计算结果与实测结果的比较表明文中所用方法能有效应用于多档连续大跨越导线的动力特性的分析计算。     

Corona power loss on bundled conductors: experimental andcomputational results

In this paper, the corona current and, hence, the corona power loss associated with bundle conductors is estimated by an iterative computational technique based on the finite-element and charge-simulation methods. The investigated bundled transmission lines consist of one, two, and three conductors. Variation of the corona power loss as a function of the number of conductors, conductors orientation, as well as the bundle spacing, is investigated. The contribution of each bundle conductor to the total corona power loss is also reported. A laboratory model was built to investigate the effectiveness of the iterative technique. It has been found that the computed results agree well with the experimental values     

合理布置分裂导线的间隔棒以减小舞动

针对结冰分裂导线舞动问题,提出了合理布置间隔棒以减小分裂导线舞动的对策.先导出气动力在分裂导线半波舞动时一个周期内的功的表达式,再分析此功与子导线的位移在档内的分布及子导线的攻角在档内分布的关系.间隔棒使子导线的扭转角减小,使子导线的冰形趋于一致,使气动力的攻角趋于一致,而作用在子导线的上的气动力是攻角的函数,从而间隔棒使作用在子导线的上的气动力趋于一致,导致分裂导线舞动的可能性增大.最后得到的结论是:对于分裂导线的半波舞动,增大档内中部的次档的长度,可减小分裂导线的半波舞动.     

ESD characteristics of a three-body system including a ground plane

Capacitance coefficients are measured for a system of three conductors positioned above a horizontal ground plane. The system is used to model the approach of a charged floating conductor (the human body) to a two-conductor system (the electronic system under test) in which either or both conductors are floating or one is grounded. Body potentials and energies are calculated for various source/sink geometries and ground plane separations; both main and second discharge conditions are analyzed. The results, which are based on the measurement of system capacitance coefficients, provide a better understanding of the basic ESD characteristics of the three-body problem. The information can be applied in the design of electronic systems and is of use in the simulation and analysis of the ESD event     

220kV同塔双回双分裂导线防覆冰舞动的研究与设计

笔者从线路设计角度进一步定性分析了单(或双分裂)导线覆冰舞动机理,指出使用现有抑舞装置应注意的问题:单导线(地线)耐张线夹和悬垂线夹的固定导线(地线)结构使固定点附近的单导线(地线)扭转刚度很大,易形成偏心覆冰并诱发舞动,进一步扩散至档内中央;绞制的导线单丝沿线不连续覆冰使单丝应力分布不均,以致导线内部不稳借助风力发生...     

Comparison of zeroth-order and harmonic expansion calculation of the electrostatic parameters of three-conductor bundles

An electrostatic field analysis of three-conductor bundles in triangular and flat (coplanar) configurations above ground is presented. The two configurations are compared from the viewpoint of bundle-to-ground capacitance, geometric mean radius, surface charge distributions, and electric field strength. Approximate results, neglecting proximity effects are firstly obtained considering a zeroth-order approach for the potential coefficient matrix. Accurate results are determined by application of the harmonic expansion method in order to correctly deal with proximity effects between individual conductors of the bundle. The latter approach yields significantly increased values for the electric field strength at certain points along the circumference of the individual conductors of the bundle. It is shown that the triangular configuration is more effective as far as corona problems are concerned.     

我国建成国际一流水平的输电线路分裂导线实验室

国家电力公司电力建设研究所2000年5月建成国际一流水平的输电线路分裂导线力学性能实验室。它包括导线微风振动、多分裂间隔棒、导线疲劳及导线需变4个实验室,实验室的建立以“立足三峡工程、满足更主同一级电压（特高压）输电的基本要求、向国际水平看齐”为指导原则,新建实验室最大机械载何为700kN,能进行2－10分裂导线的振动试验研究。它的建成已为多个国家和国家电力公司重大研究项目的试验研究提供了技术支持。《分裂导线力学性能实验室》已于2000年11月通过了国家电力公司组织的专家验收,与会专家一致认为“整体水平达到当前国际先进水平,6分裂导线以上的微风振动试验能力和试验技术、蠕变试验这到国际领先水平”。     

汽车线束等效模型及其在电磁辐射敏感度仿真中的应用

线束是导致汽车设备或系统不能满足电磁兼容限值的主要原因之一,建立计算简便且能准确反映电磁特性的线束模型是汽车电磁兼容建模的要点。文中建立了用于电磁辐射敏感度计算的线束等效模型。首先提出了等效波阻抗的定义并导出了计算方法;根据原始导线终端阻抗与等效波阻抗的大小关系将其分成最多四组等效导线,从而使复杂的线束得以简化。给出了多导体传输线单位长度电容矩阵和电感矩阵的计算方法,推导了等效导线的电感矩阵和电容矩阵。验证了基于有限元方法的电磁场仿真软件HFSS计算导线感应电流的有效性。对9根导线组成的线束等效处理及其共模电流的仿真结果表明,文中的等效方法是正确的。该等效模型能有效降低线束建模的复杂度,可用于研究汽车线束高频条件下的电磁辐射敏感度问题。     

特高压输电线路地面最大工频电场强度和导线最大弧垂特性

研究特高压输电线路几何参数与地面最大工频电场强度的关系和地面最大工频电场强度的特点,给出2种基本分裂导线排列方式的导线最小对地高度和走廊宽度。分析特高压输电导线运行温度和最大弧垂的特点。从特高压输电导线最大弧垂变化和输电运行方式两方面,讨论特高压输电导线地面最大工频电场强度限值10~12 kV/m的安全与经济的合理性。最后,提出特高压2种基本杆塔结构(猫头塔和酒杯塔)的几何参数供参考。     

Influence of a ground plane on the ESD event in electronic systems

Capacitance coefficients were measured for a basic two-conductor system, simulating the approach of a charged object (the human body) to a second object which can be floating or grounded (the equipment under test). Parameters studied include the size of the conductors, their separation, and position relative to vertical and horizontal ground planes. System equations, based on Maxwell's technique, are solved to yield the body potentials and a relative probability of discharge for the various configurations. The presence of ground planes is shown to increase the ESD (electrostatic discharge) susceptibility of small floating bodies. The results provide a better understanding to the ESD event and demonstrate the importance of ground planes in electrostatic discharge test methods     

Substation ground grids intertied with buried conductors

A fault current at a substation injected into a grounding grid that is intertied with the grounding grid of another station with buried conductors is dissipated to the ground by the grids at both the stations and by the intertie. The authors present a direct, simple, an easy-to-use approximate method to determine the ground resistance of the system as seen from the station where the current is injected and the ground potential rise at both the stations. A comparison of the results obtained with the approximate method and from the accurate method has been made. An expression for the length constant of the intertie as a function of the resistivity of the soil has been derived. The concept is useful for estimating the distance beyond which the two grids intertied with buried conductors will have a negligible effect on each other     

特高压线路多功能组合式飞车的研制

在特高压架空输电线路架线施工的过程中, 采用液压驱动多功能组合式飞车安装六分裂或八分裂导线间隔棒, 以提高工作效率和高空作业过程中施工的安全性。特高压组合式飞车, 是组合式框架结构、液压驱动, 既可以用于特高压交流的八分裂导线间隔棒安装, 也可以用于特高压直流的六分裂导线间隔棒安装, 还可以扩展到其他任何多分裂的导线间隔棒安装,有液压制动和机械制动2 种制动方式。飞车可顺利通过直线塔悬垂线夹, 便于间隔棒的安装,也可作为巡线飞车, 在线路运行维护中应用。     

基于紫外成像的高海拔分裂导线电晕起始特性研究*

高海拔电晕放电起始特性是导线电晕特性研究的重要内容之一。紫外成像仪是一种非接触式的测量放电的仪器,文中使用紫外成像仪测量了高海拔地区特高压分裂导线LGJ-720在电晕笼中的电晕放电特性。在西宁平安县特高压试验基地对LGJ-720导线在干燥、淋雨、湿导线条件下做了6分裂数下的电晕特性试验,获得了导线电晕放电紫外图谱。文章对以往的紫外图像处理算法进行改进,使用聚类和Graph Cuts算法对图像中的光斑进行分类和分割,相比传统算法保留了主光斑附近由于设备放电引起的灰度值较大的小光斑,滤除与主光斑较远且灰度值小的小光斑,提出根据光斑位置关系与灰度值进行图像分割的算法,得到了不同气象条件下导线所加电压与等效紫外光斑面积之间的关系,使用切线法获得了电晕放电起始电压,在仅考虑电晕起始电压的条件下对特高压导线选型提供参考。     

钢芯铝型线绞线与钢芯铝绞线的主要性能对比

提出了导线截面利用率的概念,基于S、Z铝型线导体,给出了几种与常用规格圆线同心绞钢芯铝绞线对应的型线同心绞钢芯铝型绞线,将两者的部分基本参数和特性作了对比。结果表明:型线同心绞的钢芯铝型线绞线比圆线同心绞钢芯铝绞线的导体截面利用率约高15%,若截面积相等,钢芯铝型线绞线的直径约减小9%,其他性能几乎相同;若两者直径相等,则钢芯铝型线绞线的导体截面积、单位质量和抗拉力较大,同时直流电阻减小而载流量增大。钢芯铝型线绞线的安装可采用常规金具,具有一定的缓覆冰性能和较好的弧垂特性,将是输电线路使用中的一种重要线种。     

双分裂导线在500kV重冰区线路中的应用

为了在广东电网500 kV坪石-曲江送电线路的30 mm及50 mm重冰区选择满足技术要求且经济合理的导线截面和分裂型式,从输送容量、电磁环境、机械特性及工程投资等方面系统地介绍了该线路的导线选型论证.计算结果表明,采用双分裂大截面导线,电磁环境干扰值能满足规程要求:机械性能上,双分裂导线方案明显优于四分裂导线方案,并...     

交流特高压变电站1000kV导线的选择

1 000 kV配电装置导线是保证特高压交流输变电工程电气技术条件的重要组成部分,电晕产生的无线电干扰和可听噪声对环境的影响是特高压导线选型和分裂形式选择的最主要因素之一。文章结合我国1 000 kV交流特高压试验示范工程的实际情况,对1 000 kV变电站导线的选型和分裂形式进行优化,确定最优分裂间距及次档距,使导线在满足电气性能和机械性能的前提下,尽可能降低对环境的不良影响。     

Power dissipation in clocking wires for clocked molecular quantum-dot cellular automata

In the molecular quantum-dot cellular automata (QCA) paradigm clocking wires are used to produce an electric field which is perpendicular to the device plane of surface-bound molecules and is sinusoidally modulated in space and time. This clocking field guides the data flow through the molecular QCA array. Power is dissipated in clocking wires due to the non-zero resistance of the conductors. We analyze quantitatively the amount of power dissipated in the clocking wires and find that in the relevant parameter range it is fairly small. Dissipation in the molecular devices themselves will likely dominate the energy budget.